Interrogating greenhouse gas emissions of different dietary structures by using a new food equivalent incorporated in life cycle assessment method

Greenhouse gas (GHG) emissions from food are of great importance for global warming effects. Life cycle assessment (LCA) method has been widely used in this field. In previous studies, food mass was mainly used as the functional unit in LCA, which cannot cover the environmental load of food products in terms of nutrition value. Other functional units are less applied and mostly have specific application scenarios. In this study, food mass and nutrition value were both taken into consideration in the development of a new food equivalent (FE) unit incorporated in LCA (FE-LCA) to investigate the greenhouse gas (GHG) emission and nutritional level (FEC) of different food and dietary structure. GHG emissions from 15 food products based on either same mass or FE measured and compared by LCA showed that legumes, grains and nuts are low-carbon food product, whereas beef can provide the highest carbon emission. Grains, legumes, nuts and chicken have a higher nutritional value the intake of anti-seasonal vegetables and anti-seasonal fruits should be reduced while more seasonal foods should be consumed. From GHG emission results of 9 dietary structures, Argentine diet presented the highest carbon emission due to extensive beef intake. The lowest GHG emission referred to Vegan diet but has a low FEC of 75.90 cannot supply the nutritional needs of human health. New Nordic Diet, Mediterranean Diet, Chinese Diet and Dutch Diet with reasonable GHG emission were recommended. They were characterized by a more balanced consumption of various food groups without a clear preference for a particular food group. In conclusion, the FE-LCA method is the most suitable method when evaluating food production.